Study on Metal Ion Binding Properties of Zea Mays Centrin(ZmCen)
Zea mays L.centrin(ZmCen)contains four members of calmodulin family with EF-hand do-mains,which exert biological functions by binding calcium ions in organisms.In this paper,the full-length pro-tein of ZmCen,its N-terminal and C-terminal truncated proteins and four mutant proteins of ion binding sites were expressed and purified by prokaryotic expression system.The conformational changes and binding properties of ZmCen binding to metal ion Tb3+were studied by circular dichroism spectrometry(CD),fluorescence spectrome-try,Tb3+sensitized fluorescence spectrometry and isothermal titration calorimetry(ITC).The results showed that the helix increased after ZmCen bound to Tb3+.The binding ratio of ZmCen to Tb3+is 1∶4,and the binding order of Tb3+to the four EF-hand domains of ZmCen is Ⅲ-IV-1-Ⅱ.ITC results show that the binding constants of N-terminal truncated protein and C-terminal truncated protein of ZmCen with Ca2+ions are KNI=5.814 × 105,KNII=2.818 x 105 and KC=1.068 × 105,respectively,that is,KN is greater than KC.This study provides a theo-retical foundation for clarifying the function of ZmCen.
万方数据
维普
